Core Structure Components
Temperature Sensing Element: Uses high-purity platinum wire (Pt100 or Pt1000), conforming to IEC 60751 standard, with a linear resistance-temperature relationship and a resistance of 100Ω or 1000Ω at 0℃;
Protective Tube: Made of 316L stainless steel or Hastelloy C276, with a wall thickness of 1.0–2.0 mm, corrosion-resistant and erosion-resistant, suitable for strong acid and high-temperature steam environments;
Threaded Interface: Fixed metric threads (e.g., M12×1.5, M16×1.5) or imperial pipe threads (e.g., G1/2, NPT 1/2), directly screwed into the pre-reserved threaded hole on the equipment, with non-adjustable insertion depth;
Sealing Structure: PTFE sealing tape or high-temperature silicone gasket is used between the threads to ensure no media leakage under pressure ≤10 MPa;
Wiring Method: Standard three-wire system (to eliminate the influence of lead resistance) or four-wire system (for high-precision measurement), with fluoroplastic insulation layer for the leads (temperature resistance ≥250℃);
Junction Box: IP65/IP67 protection rating, built-in terminal block, supports cable gland, moisture-proof and dustproof.
Typical Application Scenarios and Industry Standards
Chemical and Petrochemical: Reactor wall temperature monitoring, distillation column temperature distribution control, compliant with ASME B16.34 pressure vessel specifications;
Energy and Power: Steam pipelines, boiler superheaters, nuclear power cooling circuits, meeting both API 650 and IEC 60751 certifications;
Pharmaceutical and Food: Sterilization temperature monitoring in CIP/SIP cleaning systems, materials certified for FDA/USP Class VI biocompatibility;
Metallurgy and Machinery: Heat treatment furnaces, die-casting mold surface temperature acquisition, resistant to periodic thermal shock;
Standards Basis:
IEC 60751: Platinum resistance thermometer calibration characteristics and accuracy definition;
ASME B1.20.1: NPT thread sealing standard;
ISO 228-1: G series parallel pipe thread specifications;
GB/T 30423-2013: Chinese industrial platinum resistance thermometer technical conditions.
Differences Between Fixed and Adjustable Threaded Types
|
Dimension |
Fixed Threaded Type |
Adjustable Threaded Type |
|
Insertion Depth |
Fixed and non-adjustable, locked after installation |
Insertion depth can be adjusted by rotation, facilitating on-site calibration |
|
Sealing Reliability |
Extremely high, suitable for high pressure (>5 MPa) and hazardous media |
Moderate, relies on gaskets, prone to leakage under long-term high pressure |
|
Vibration Resistance |
Excellent, rigid connection with no risk of loosening |
Good, but threads may loosen due to long-term vibration |
|
Installation Method |
One-time installation, requires shutdown and depressurization |
Can be fine-tuned online, some models support replacement under pressure |
|
Maintenance Cost |
Low (no frequent calibration required) |
High (requires regular inspection of thread tightening and sealing) |
|
Applicable Environment |
High pressure, high temperature, corrosive, non-removable systems |
Normal pressure, frequent calibration required, scenarios where process shutdown is permissible |
Mainstream Product Models and Naming Conventions
Industry Standard Naming Format:
WZP-430-PT100-M12×1.5
WZP: Industrial Platinum Resistance Thermometer (National Standard Code)
430: Structural Form (Fixed Threaded Type)
PT100: Index Number
M12×1.5: Thread Specification (Metric)
Optional Suffixes: -IP67, -316L, -4WIRE
Typical Models from International Manufacturers:
WIKA TR10: Industrial standard type, supports three-wire/four-wire, temperature resistance up to 600℃;
Endress+Hauser TR15-A1F931HLKS00B: Modular design, with HART communication protocol;
Honeywell 1000-RTD-FIX: Explosion-proof type (Ex ia IIC T4), used in petrochemical hazardous areas.
Installation and Maintenance Guidelines
Installation Torque: For M12×1.5 threads, a torque of 15–20 N·m is recommended. Use a torque wrench to avoid overtightening and thread deformation;
Sealing Treatment: Apply high-temperature thread sealant (such as Loctite 577) to the threads. The use of PTFE tape is prohibited at high temperatures (>200℃);
Thermal Conductivity Optimization: The inner wall of the threaded hole should be clean and rust-free. A small amount of thermal grease can be applied to improve response speed;
Regular Inspection: Check every 6 months for loose threads, corrosion of the protective tube, and decreased insulation resistance;
Prohibited Operations: Do not use power tools to forcibly screw in the probe, and do not disassemble under pressure.
The fixed-thread type platinum resistance thermometer is the "silent guardian" of industrial process control – it doesn't prioritize rapid response, but with its ultimate sealing, vibration resistance, and long-term stability, it provides an irreplaceable temperature reference for process safety in harsh high-pressure and high-temperature environments.
